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Biomedical subjects

I A Orr

Publications and source records attributed to I A Orr.

13 recordsLinked to original sources
PubMed1989

Characteristics of the Pharmaseal continuous flushing device.

Pharmaseal continuous flushing devices were tested with regard to flow characteristics into simulated arterial and venous pressure systems. Two driving pressures were used and it was found that variation in driving pressure made a significant difference to the flow, while arterial or venous pressure made no significant difference. The flow devices had a wide variation although they were all of the same type. The fluid volume delivered was in the region of 100 ml in a 24-hour period.

Equipment Design↗
PubMed1988

Comparison of sufentanil-oxygen and fentanyl-oxygen anaesthesia for coronary artery bypass grafting.

Haemodynamic variables were compared in 40 adults undergoing coronary artery bypass grafting during anaesthesia induced with either sufentanil 5 micrograms kg-1 or fentanyl 25 micrograms kg-1 in combination with pancuronium 0.1 mg kg-1. Further doses of sufentanil 2.5 micrograms kg-1 or fentanyl 12.5 micrograms kg-1 were given before skin incision and again before sternotomy. All patients were receiving beta-adrenoceptor blocking therapy. Satisfactory induction of anaesthesia was produced with both drugs and opioid supplementation prevented any marked haemodynamic response to skin incision and to sternotomy. Following induction of anaesthesia, sufentanil produced the greater decrease in mean arterial pressure and left ventricular stroke work index which continued throughout the study. This suggests that, in the doses used in this study, sufentanil is preferable to fentanyl in patients with coronary artery disease.

Anesthesia, General↗
PubMed1988

A pharmacokinetic study of midazolam in paediatric patients undergoing cardiac surgery.

Midazolam 0.3 mg kg-1 was given as a single dose to three groups of children undergoing cardiac surgery to determine its pharmacokinetic profile in this situation. The first group, undergoing closed heart surgery, received the midazolam during the operation. The other groups underwent cardiopulmonary bypass (CPB) with and without complete circulatory arrest. Mean clearance was 512 ml kg-1 h-1 and mean elimination half-lives were 3.3 h following CPB, with a tendency to a higher clearance in those children who had not undergone bypass. In a subsequent part of the study, 10 children received an infusion of midazolam 0.05 mg kg-1 h-1, in combination with intermittent doses of morphine, in the postoperative period. Mean plasma midazolam concentrations consistent with adequate sedation were 80-100 ng ml-1 during the infusion. One child who had not undergone CPB had very low plasma concentrations of midazolam with the same rate of infusion, consistent with the tendency for higher clearance in this group in the bolus pharmacokinetic study.

Cardiac Surgical Procedures↗
PubMed1987

Haemodynamic effects of vecuronium, pancuronium and atracurium in patients with coronary artery disease.

Thirty patients with ischaemic heart disease scheduled for coronary artery bypass grafting were randomly allocated to three equal groups. Following morphine, hyoscine and pentobarbitone premedication, anaesthesia was induced with diazepam 0.3 mg kg-1. Five minutes later neuromuscular blockade was induced with pancuronium 0.1 mg kg-1, vecuronium 0.1 mg-1 or atracurium 0.5 mg kg-1, followed after 6 min by fentanyl 25 micrograms kg-1. Pancuronium and atracurium caused significant increases in heart rate, while vecuronium induced little change. Systemic vascular resistance decreased significantly from 1515 dyn s cm-5 to 1200 dyn s cm-5 following atracurium. Cardiac index was increased transiently in the atracurium group, but a more sustained increase was observed following pancuronium. Nine patients in the atracurium group showed skin flushing and one developed skin weals.

Atracurium↗
PubMed1987

Midazolam sedation following open heart surgery.

Midazolam given as hourly intermittent injections was compared with the same dose given by infusion for postoperative sedation in patients after cardiopulmonary bypass. A stable concentration was rapidly attained with the infusion whereas 6-8 h was required to attain stable plasma (trough) concentrations in the intermittent injection group. Plasma concentrations decreased rapidly to low values within 6 h of discontinuation of therapy. High plasma concentrations and a long (16 h) half-life were noted in one patient who may be a slow metabolizer of the drug.

Adult↗
PubMed1985

Pharmacokinetics of diazepam and midazolam when used for sedation following cardiopulmonary bypass.

The water-soluble benzodiazepine, midazolam, was compared with diazepam for postoperative sedation in patients following cardiopulmonary bypass. Midazolam in repeated doses produced a stable plasma concentration within 4 h, showed no tendency to cumulation and was cleared rapidly following discontinuation. Similar doses of diazepam given with the same frequency produced plasma concentrations which were still increasing at the time of discontinuation and which were still greater than their baseline values 24 h later.

Anesthesia, General↗
PubMed1985

Entonox hazard.

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Anesthesia, Inhalation↗
PubMed1983

Post-thoracotomy pain relief: combined use of cryoprobe and morphine infusion techniques.

In a reported study we found that freezing of the intercostal nerves under direct vision at thoracotomy provided better postoperative analgesia than im morphine on demand. Infusions of morphine were also more effective than when used by the intramuscular route. The benefit on the eighth postoperative day was greatest following the use of the cryoprobe. Further studies were carried out to evaluate the benefit of combining 'cryoprobe' analgesia with infusions of morphine. The combined use of morphine infusion and a cryoprobe did not produce greater postoperative pain relief than the use of the cryoprobe alone with im morphine on demand.

Adult↗
PubMed1981

Improved pain relief after thoracotomy: use of cryoprobe and morphine infusion.

In a randomised controlled trial carried out during the first to days after thoracotomy patients who had had intercostal nerves frozen with a cryoprobe or were given morphine by continuous intravenous infusion had significant less pain at rest than patients given intramuscular morphine. Differences between the groups with respect to pain on movement and during physiotherapy were not significant. Pain was estimated using visual analogue scales, and an arc sine transformation was carried out on values obtained from these scales before comparison using an analysis of variance. The trial did not distinguish between the cryoprobe and infusion treatment. The simplicity of the cryoprobe had much to commend it, but in units without access to this equipment a small infusion pump offers a satisfactory alternative.

Adult↗